The present invention relates, in general, to an improved surgical biopsy device and, more particularly, to an improved firing mechanism for use in a surgical biopsy device.
The diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other disorders has long been an area of intense interest in the medical community. Non-invasive methods for examining tissue and, more particularly, breast tissue include palpation, X-ray imaging, MRI imaging, CT imaging, and ultrasound imaging. When a physician suspects that tissue may contain cancerous cells, a biopsy may be done using either an open procedure or in a percutaneous procedure. In an open procedure, a scalpel is used by the surgeon to create an incision to provide direct viewing and access to the tissue mass of interest. The biopsy may then be done by removal of the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). In a percutaneous biopsy, a needle-like instrument is inserted through a very small incision to access the tissue mass of interest and to obtain a tissue sample for examination and analysis. The advantages of the percutaneous method as compared to the open method are significant: less recovery time for the patient, less pain, less surgical time, lower cost, less disruption of associated tissue and nerves and less disfigurement. Percutaneous methods are generally used in combination with imaging devices such as X-ray and ultrasound to allow the surgeon to locate the tissue mass and accurately position the biopsy instrument.
Generally there are two ways to percutaneously obtain a tissue sample from within the body, aspiration or core sampling. Aspiration of the tissue through a fine needle requires the tissue to be fragmented into small enough pieces to be withdrawn in a fluid medium. Application is less intrusive than other known sampling techniques, but one can only examine cells in the liquid (cytology) and not the cells and the structure (pathology). In core biopsy, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen or paraffin section. The type of biopsy used depends mainly on various factors and no single procedure is ideal for all cases.
A number of core biopsy instruments which may be used in combination with imaging devices are known. Spring powered core biopsy devices are described and illustrated in U.S. Pat. Nos. 4,699,154, 4,944,308, and Re. 34,056. Aspiration devices are described and illustrated in U.S. Pat. Nos. 5,492,130; 5,526,821; 5,429,138 and 5,027,827.
U.S. Pat. No. 5,526,822 describes and illustrates an image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument which takes multiple tissue samples without having to re-puncture the tissue for each sample. The physician uses this biopsy instrument to xe2x80x9cactivelyxe2x80x9d capture (using the vacuum) the tissue prior to severing it from the body. This allows the physician to sample tissues of varying hardness. The instrument described in U.S. Pat. No. 5,526,822 may also be used to collect multiple samples in numerous positions about its longitudinal axis without removing the instrument from the body. A further image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument is described in commonly assigned U.S. application Ser. No. 08/825,899, filed on Apr. 2, 1997 and in U.S. Pat. Nos. 6,007,497; 5,649,547; 5,769,086; 5,775,333; and 5,928,164. A handheld image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instrument is described in U.S. Pat. No. 6,086,544 and in U.S. Pat. No. 6,120,462. The instrument described therein moves drive motors and other electronic components into a control unit separate from and remotely located from the biopsy probe. Biopsy probe cutter rotational and translational motion is transferred from the motors in the control unit to the biopsy probe via flexible coaxial cables. This arrangement greatly improves the cleanability of the reusable hardware that remains in close proximity to the biopsy site as well as improves the life and durability of the electric motors and electronic components now remotely located from the biopsy probe. The biopsy instrument described and illustrated in U.S. Pat. No. 6,086,544 and in U.S. Pat. No. 6,120,462 was designed primarily to be a xe2x80x9chand heldxe2x80x9d instrument to be used by the clinician in conjunction with real time ultrasound imaging. The majority of breast biopsies done today, however, utilize an x-ray machine as the imaging modality. Using x-ray requires that the biopsy instrument be affixed to the x-ray machine by some type of bracket arrangement. Since the biopsy instrument is fixed to a portion of the x-ray machine there is now a need for a means to conveniently advance the biopsy probe into the breast. It is highly desirable to have the capability to xe2x80x9cfirexe2x80x9d the biopsy probe via some type of stored energy system, to rapidly advance the biopsy probe into the target area of the breast. Such a instrument, utilizing the cable driven arrangement of Hibner et al, would inherit the cleanability and durability attributes of the Hibner et al instrument while providing the added flexibility to attach the biopsy instrument to an x-ray machine and xe2x80x9cfirexe2x80x9d the probe into the breast. Several image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instruments are currently sold by Ethicon Endo-Surgery, Inc. under the Trademark MAMMOTOME(trademark).
Many breast biopsies done today utilizing image-guided, vacuum-assisted, percutaneous, coring, breast biopsy instruments are still done utilizing x-ray machine. In actual clinical use the biopsy instrument (probe and driver assembly) is mounted to the three axis positioning head of the x-ray imaging machine. The three axis positioning head is located in the area between the x-ray source and the image plate. The stereotactic x-ray machines are outfitted with a computerized system which utilizes two x-ray images, of the breast taken at two different positions to calculate the x, y and z axis location of a suspect abnormality. In order to take the stereo x-ray images the x-ray source must be movable. The x-ray source is, therefore, typically mounted to an arm which, at the end opposite the x-ray source, is pivotally mounted to the frame in the region of the x-ray image plate. In a breast biopsy the breast is placed between the x-ray source and the image plate. In order to take the necessary stereo images, the clinician manually positions the x-ray source on one side and then the other of the center axis of the machine (typically 15-20 degrees to each side of the center axis), obtaining an x-ray image on each side of the breast. The computer will then, calculate the precise x, y and z location of the suspect abnormality in the breast and automatically communicate to the clinician or directly to the positioning head the targeting coordinates for the biopsy device. The clinician can there manually, or automatically, position the biopsy probe into the breast at the precise location of the abnormality.
There are generally two styles of stereotactic x-ray machines in wide spread use for breast imaging. One style is a prone stereotactic x-ray machine, because the patient lies face down on a table during the x-ray and biopsy procedures. The other style, in more wide spread use, is an upright stereotactic x-ray machine. The center axis of the upright imaging machine is vertical to the floor and the patient sits in front of the machine during the x-ray and biopsy procedures.
It would, therefore, be advantageous to design an image-guided, vacuum assisted, percutaneous, coring, cable driven breast biopsy instrument which may be conveniently mounted to an x-ray machine, and incorporate a firing mechanism used to rapidly advance the biopsy probe into the breast.
The present invention is directed to a biopsy instrument including a base assembly including a firing mechanism moveably attached to a distal end of the base assembly, a probe assembly detachably mounted to the base assembly and a drive assembly detachably mounted to the cutter assembly. The probe assembly includes a cutter assembly and a piercer assembly. The cutter assembly includes a cutter and a gear mechanism adapted to move the cutter. The piercer assembly includes a piercer and a probe mount. The piercer includes a distal port, a vacuum lumen and a central lumen wherein the central lumen is adapted to receive the cutter. The probe mount includes a central lumen adapted to allow the cutter to pass through the probe mount and a fork coupling detachably connected to the firing mechanism. The drive assembly, being detachably mounted to the cutter assembly, includes a flexible drive shaft operatively connected to the gear mechanism. Further, a proximal end of the probe housing is slideably movable with respect to a distal end of the cutter assembly.
The present invention is further directed to a biopsy instrument including a base assembly including a firing mechanism, a probe assembly detachably mounted to the base assembly, a piercer assembly and a drive assembly detachably mounted to the cutter assembly. The firing mechanism including a firing fork moveably attached to a distal end of the base assembly and a firing assembly attached to the firing fork. The probe assembly including a cutter assembly and a gear mechanism. The cutter assembly including a cutter with a central lumen extending through the cutter, a sharpened edge at a distal end of the cutter and a first drive gear. The gear mechanism adapted to move the cutter, wherein the gear mechanism includes a second drive gear adapted to mesh with the first drive gear. The piercer assembly including a piercer and a probe mount. The piercer including distal tissue port adapted to receive tissue, a first central lumen extending from a proximal end of the piercer to the tissue port, the central lumen being adapted to receive the cutter and a vacuum lumen fluidly connected to the tissue port. The probe mount connecting the piercer to the cutter assembly wherein a proximal end of the probe housing is slideably moveable with respect to a distal end of the cutter assembly. The probe mount comprising including a second central lumen adapted to allow the cutter to pass through the probe mount to the first central lumen and a fork coupling detachably connectable to the firing fork. The drive assembly including a flexible drive shaft adapted to be connected at its proximal end to a control unit including a motor and transmission adapted to connect a distal end of the flexible drive shaft to the cutter assembly, wherein rotation of the flexible drive shaft rotates the second drive gear.